Apparatus for disintegrating and bleaching pulp

ABSTRACT

Apparatus for disintegrating and bleaching a cellulose pulp which is delivered into a bleaching vessel while in a compacted state and is disintegrated by means creating a whirling effect at the top of the bleaching vessel in the presence of a gaseous bleaching agent and is distributed onto a column of disintegrated pulp in the vessel and is then removed therefrom.

United States Patent [191 Schleinkofer APPARATUS FOR DISINTEGRATING AND BLEACHING PULP [75] Inventor: Rudi William Schleinkofer, Nashua,

[73] Assignee: Sunds Aktiebolag, Sundsvall,

Sweden [22] Filed: Apr. 17, 1973 [21] Appl. No; 351,852

Related US. Application Data [60] Continuation of Ser. No. 128,124, March 25, 197-1,

abandoned, which is a division of Ser. No. 771,071, Oct. 28, 1968, abandoned.

[30] Foreign Application Priority Data Nov. 9, 1967 Sweden 15383/67 [52] US. Cl. 241/47, 241/188 R [51] Int. Cl. B02c 13/18 [58] Field of Search 241/18, 38, 39, 47, 62,

[ Apr. 30, 1974 [56] References Cited UNITED STATES PATENTS 246,992 9/1881 Anderson 241/188 R 3,219,286 11/1965 Doyle et a1. 241/188 A 3,348,779 10/1967 Andrews 241/39 3,600,477 8/1971 Friedel et al 241/18 Primary ExaminerGranville Y. Custer, Jr.

Attorney, Agent, or FirmPierce, Scheffler & Parker 57 ABSTRACT Apparatus for disintegrating and bleaching a cellulose pulp which is delivered into a bleaching vessel while in a compacted state and is disintegrated by means creating a whirling effect at the top of the bleaching vessel in the presence of a gaseous bleaching agent and is distributed onto a column of disintegrated pulp in the vessel and is then removed therefrom.

17 Claims, 7 Drawing Figures pondslcm APPARATUS FOR DISINTEGRATING AND BLEACHING PULP This is a continuation of application Ser. No. 128,124, filed Mar. 25, 1971, now abandoned, which is a divisional of my earlier filed parent application Ser. No. 771,071, filed Oct. 28, 1968, now abandoned in favor of continuation Ser. No. 143,643, filed May 14, 1971, now issued as US. Pat. No. 3,703,435, dated Nov. 21, 1972.

When bleaching cellulose pulp by means of gaseous bleaching agents, such as oxygen, the very bleaching process should be carried out at a high pulp consistency, 90 percent, preferably at 10 30 percent and preferentially at about 20 percent, and at a high pressure. The compressing of the pulp, required for obtaining the above mentioned consistencies, and the feeding of the pulp into the bleaching vessel counter the high pressureresults in the pulp receiving a compact consistency which is undesirable for carrying out the bleaching process. In order that the bleaching process shall take place rapidly and uniformly it is required that the pulp is in a finely disintegrated and fluffy state with a considerable porosity and an exposed surface.

The present invention has for its object, in connection with the bleaching, to transform the pulp into a state of the kind just mentioned, so that a rapid and uniform bleaching is obtained. Fundamentally this is done in such a manner that the pulp is introduced into the upper part of an upright bleaching vessel, that a gasfilled space is maintainedwithin said upper part and that, the pulp as it enters said gas-space is subjected to a centrifugal mechanical working in a direction extending substantially transversely of the (substantially vertical) falling direction of the pulp within the gas-filled space, so that the pulp is finely broken up or disintegrated and/or is spread within said space. The mechanical working of the pulp may be so strong that a considerable part of the pulp is caused to flow downwards and upwards several times within the gas-filled space before occupying its rest position on the upper surface of the column of pulp. In that case the pulp, when viewed in a horizontal plane, may first be caused to move helically, then substantially rectilinearly and, finally, to perform a whirling motion. The working of the pulp may be carried out while supplying, preferably continuously supplying, a gaseous bleaching agent.

Primarily the present method is intended to be used in bleaching vessels, the gas-spaces of which are under overpressure from about 5 up to about 20 kilopreferably about 6 to about kiloponds/cm and preferentially about 8 to about 10 kiloponds/cm", but it may also be used, advantageously, in bleaching vessels the gas-spaces of which are under atmospheric pressure or in which there prevails low pressure.

One form of apparatus for carrying out the method may comprise, fundamentally, an upright (vertical or substantially vertical) bleaching vessel, at least one supply conduit for pulp and at least one supply conduit for supplying a gaseous bleaching agent at the upper portion of the bleaching vessel and at least one working member positioned in the way of the pulp arriving from the mouth of the supply conduit and falling down into the bleaching vessel, said working member being adapted to move rapidly substantially transversely of the free falling direction of the pulp and, being also adapted during its motion, to disintegrate and spread the falling pulp, for the purpose of creating favorable conditions of reaction between the gaseous bleaching agent and the pulp introduced into the bleaching vesvessel,

FIGS. 3, 3a, 4, 5 and 6 illustrate various embodiments of details of the apparatus according to the invention.

The bleaching vessel 1 is here shown to be a conventional downward-flow tower having a pulp supply conduit 2, connected to the top of the tower, and an outlet conduit 3 for treated pulp at the bottom of the tower. At the lower portion of the tower there are, in a manner known per se, mounted dilution nozzles 4 and propeller stirring means 5 for the purpose of providing for a uniform decrease of the consistency of the pulp. In the way of the pulp falling down from the conduit 2 there is provided a fine-disintegrating member 6, preferably embodied as shown in FIG. 2 and 3 as a rotatable disc 7 having a number of upwardly projecting fillets 8. The fine-disintegrating member 6 is supported by a shaft 9, (see FIG. 2) journalled in a bracket 10 and adapted to be driven by a motor 11. The outer diameter of the disc 7 and the fillets 8 may be one to five times, preferably two to four times, and preferentially about three times the diameter of the pulp inlet of the tower. The height of the fillets 8 usually is 2 3 cm butheights of between 1 25cm may prove suitable under various conditions. Although not shown the fillets 8 may form an angle to the plane of the disc 7 deviating from so that upon rotation of the disc the upper edges of the fillets either move ahead of or after the lower edges, when seen in the direction of rotation. As appears from FIGS. 3 and 4 the fillets may extend either substantially radially (the fillets 8 of FIG. 3.) or in a direction deviating from the radial direction (the fillets 12 of FIG. 4). In that case the fillets are located between two radial planes and the arrangement preferably is such that there is only one such group of fillets. It is possible also to dispense with the disc 7 and, instead, to secure the fillets 8 in a hub 8a provided on the shaft 9 as shownin FIG. 3a, said hub having a diameter which is smaller than the diameter of the disc 7. In an embodiment of that kind two, three or more systems of fillets may, at suitable intervals, be provided in the vertical direction on the shaft 9, as seen in FIG. 3a. Numeral 13 indicates a conduit for supplying gaseous bleaching agent. Also a plurality of such supply conduits may be provided.

In the embodiments according to FIGS. 5 and 6 the fillets have been replaced by rotatable pegs l4 and, respectively 15 and 16. The pegs 14 (FIG. 5) are, when seen in the direction of movement of the falling pulp, arranged substantially axially of the shaft 9 and preferably adapted to co-operate with stationary pegs 17, which are also arranged substantially axially to facilitate disintegration. The pegs 15 (FIG. 6) which are located in the pulp supply conduit adjacent to the top of the container and extend substantially transversely or radially of the rotary shaft 9 may be arranged substantially helically in the axial direction of the bleaching vessel at equal or varying pitch and the stationary pegs 18, with which the pegs 15 co-operate extend also substantially transversely or radially toward the rotary shaft 9. In the embodiment according to FIG. the pegs 14 are supported by a disc .19.

The mode of operation of the apparatus is as follows:

Throughthe conduit 2 pulp is introduced into the upper part of the tower 1. During its passage through the conduit 2 the pulp constitutes an efficient lock against the overpressure from inside the tower. The pulp then falls downwards and will then come into contact with the rotating fillets and/or pegs, the pulp being then disintegrated. During this operation the disintegrated pulp will be thrown out towards the periphery of the bleaching tower and the intended distribution of the pulp is obtained over the entire interior cross sectional area of the tower. During their rotation the fine-disintegration members also provide for a fan action generating a favorable gas circulation in the upper gas-filled space of the tower, in accordance with what is indicated by the arrows in FIG. 2. In order that the intended effect of fine disintegration shall be obtained the number of revolutions per minute of the shaft 9 should be from about 100 to 3,000 r.p.m., possibly also higher. A suitable number of revolutions is about 1,500 r.p.m. Normally, a number of revolutions of between 200 to 2,000 r.p.m. will provide for the intended effect.

The invention is not limited to the embodiments shown and described. Thus, the intended technical effect can be obtained by using fine-disintegration members, adapted to work the pulp along its free falling direction within the tower. Also, said effect may be obtained by means of fine-disintegration members, arranged to work the pulp straight or obliquely to the same, and also through a combined working of the pulp along the free falling direction thereof and/or obliquely to said direction and/0r transversely of said direction, in which case the combined working should include at least two of the aforementioned working directions. The upper and/or lower edges of the fillets may be toothed, undulated or embodied in some other, similar way.

What is claimed is:

1. Apparatus for finely disintegrating and bleaching fibrous pulp with a gaseous bleaching agent comprising a substantially vertical bleaching vessel having a circular cross section, at least one first conduit connected to the upper portion of said vessel for supplying pulp thereto in a compacted state serving to prevent escape of the gaseous bleaching agent therethrough, at least one second conduit connected to said vessel for supplying a gaseous bleaching agent above atmospheric pressure to said vessel, said vessel containing a column of disintegrated pulp below the upper portion thereof, a rotatable shaft extending into the outlet end of said first conduit means, working means including a plurality of disintegrating members mounted for rotation with said rotatable shaft in the line of passage of the pulp supplied to said vessel, said working means creating a whirling effect for distributing the pulp onto the surface of the column of disintegrated pulp in said vessel and disintegrating the incoming pulp to facilitate bleaching thereof by the gaseous bleaching agent and means for removing disintegrated pulp from the bottom of said vessel.

2.,Apparatus as claimed in claim 1 wherein the axis of the outlet end of said first conduit and said rotatable shaft are disposed substantially vertically.

3. Apparatus as claimed in claim 1 wherein said working means is disposed within the outlet end of said first conduit means.

4. Apparatus as claimed in claim 1 wherein said working means is disposed beyond the outlet end of said first conduit means but adjacent thereto.

5. Apparatus as claimed in claim 3 wherein said plurality of disintegrating members comprise elements extending substantially radially from and mounted on said rotatable shaft and said shaft is disposed substantially vertical.

6. Apparatus as claimed in claim 5 wherein said disintegrating elements comprise a group of pegs spaced along the axis of said rotatable shaft.

7. Apparatus as claimed in claim 6 and further comprising stationary pegs arranged in groups radially and inwardly within the outlet end of said first conduit means and mounted on the inner wall thereof to cooperate with the pegs mounted for rotation on said rotatable shaft for disintegrating the pulp.

, 8. Apparatus as claimed in claim 4 wherein said disintegrating members comprise a first group and a second group of a plurality of pegs, said first group of pegs being mounted for rotation with said rotatable shaft about the axis thereof and extending in the interspace between two parallel planes, which are perpendicular to said axis and said second group of pegs being mounted stationary and extending in said interspace to cooperate with said first group of pegs for disintegrating the pulp.

9. Apparatus as claimed in claim 8 and further comprising a disc mounted on the end of said rotatable shaft and transversely to the axis thereof for rotation therewith and wherein said rotatable pegs are mounted on the upper side of said disc.

10. Apparatus as claimed in group 4 wherein said working means comprises at least one group of a plurality of vanes mounted on said rotatable shaft.

11. Apparatus as claimed in claim 4 wherein said working means comprises at least two groups of a plurality of vanes mounted on said rotatable shaft and arranged at intervals along said shaft.

12. Apparatus as claimed in claim 4 and further comprising a disc mounted on theend of said rotatable shaft and a plurality of vanes mounted on theupper side thereof for rotation with said disc in a substantially horizontal plane. I

13. Apparatus as claimed in claim 12 wherein said vanes are disposed substantially radially of said rotatable shaft.

l4. Apparatus as claimed in claim 12 wherein said vanes are disposed at an angle to the radii of said rotatable shaft.

15. Apparatus as claimed in claim 12 wherein the upper edges of said vanes are serrated.

16. Apparatus as claimed in claim 1 and further comprising means for rotating said rotatable shaft at from about to about 3,000 revolutions per minute.

17. Apparatus as claimed in claim 4 wherein said working means has an outer diameter from about one to five times the diameter of the outlet end of said first conduit. 

1. Apparatus for finely disintegrating and bleaching fibrous pulp with a gaseous bleaching agent comprising a substantially vertical bleaching vessel having a circular cross section, at least one first conduit connected to the upper portion of said vessel for supplying pulp thereto in a compacted state serving to prevent escape of the gaseous bleaching agent therethrough, at least one second conduit connected to said vessel for supplying a gaseous bleaching agent above atmospheric pressure to said vessel, said vessel containing a column of disintegrated pulp below the upper portion thereof, a rotatable shaft extending into the outlet end of said first conduit means, working means including a plurality of disintegrating members mounted for rotation with said rotatable shaft in the line of passage of the pulp supplied to said vessel, said working means creating a whirling effect for distributing the pulp onto the surface of the column of disintegrated pulp in said vessel and disintegrating the incoming pulp to facilitate bleaching thereof by the gaseous bleaching agent and means for removing disintegrated pulp from the bottom of said vessel.
 2. Apparatus as claimed in claim 1 wherein the axis of the outlet end of said first conduit and said rotatable shaft are disposed substantially vertically.
 3. Apparatus as claimed in claim 1 wherein said working means is disposed within the outlet end of said first conduit means.
 4. Apparatus as claimed in claim 1 wherein said working means is disposed beyond the outlet end of said first conduit means but adjacent thereto.
 5. Apparatus as claimed in claim 3 wherein said plurality of disintegrAting members comprise elements extending substantially radially from and mounted on said rotatable shaft and said shaft is disposed substantially vertical.
 6. Apparatus as claimed in claim 5 wherein said disintegrating elements comprise a group of pegs spaced along the axis of said rotatable shaft.
 7. Apparatus as claimed in claim 6 and further comprising stationary pegs arranged in groups radially and inwardly within the outlet end of said first conduit means and mounted on the inner wall thereof to cooperate with the pegs mounted for rotation on said rotatable shaft for disintegrating the pulp.
 8. Apparatus as claimed in claim 4 wherein said disintegrating members comprise a first group and a second group of a plurality of pegs, said first group of pegs being mounted for rotation with said rotatable shaft about the axis thereof and extending in the interspace between two parallel planes which are perpendicular to said axis and said second group of pegs being mounted stationary and extending in said interspace to cooperate with said first group of pegs for disintegrating the pulp.
 9. Apparatus as claimed in claim 8 and further comprising a disc mounted on the end of said rotatable shaft and transversely to the axis thereof for rotation therewith and wherein said rotatable pegs are mounted on the upper side of said disc.
 10. Apparatus as claimed in group 4 wherein said working means comprises at least one group of a plurality of vanes mounted on said rotatable shaft.
 11. Apparatus as claimed in claim 4 wherein said working means comprises at least two groups of a plurality of vanes mounted on said rotatable shaft and arranged at intervals along said shaft.
 12. Apparatus as claimed in claim 4 and further comprising a disc mounted on the end of said rotatable shaft and a plurality of vanes mounted on the upper side thereof for rotation with said disc in a substantially horizontal plane.
 13. Apparatus as claimed in claim 12 wherein said vanes are disposed substantially radially of said rotatable shaft.
 14. Apparatus as claimed in claim 12 wherein said vanes are disposed at an angle to the radii of said rotatable shaft.
 15. Apparatus as claimed in claim 12 wherein the upper edges of said vanes are serrated.
 16. Apparatus as claimed in claim 1 and further comprising means for rotating said rotatable shaft at from about 100 to about 3, 000 revolutions per minute.
 17. Apparatus as claimed in claim 4 wherein said working means has an outer diameter from about one to five times the diameter of the outlet end of said first conduit. 